Solenoid construction



Aug- 21, 1945 R. s. MILLER ETAL 2,383,332

SOLENOID CONSTRUCTION Filed Julif 2l, 1941 2 Sheets-Sheet l n] iFay/mon] .S Mil/er Aug. 2l, 1945. R. s. MILLER ETAL SOLENOIDCONSTRUCTION- Filed July 21, 1941 2 ysheets-sheet 2 INVENTOR.

Fqymma' JT /V/'l/er 71' ami/ Seidel maf/Mw "other magnetic losses.

Patented ug.`2l, 1945 UNITED STATES PATENT oFFlcE soLENom coNs'raUc'rroNRaymond S. Miller and Kamill Seidel. Detroit,

Mich., assignors to `"ickers, Incorporated, De-

troit, Mich., a corporation of Michigan Application .my 21, 1941, serialNo. 403,352

' 7 claims. (ci. irs-341) construction but none of these has beencompletely successful. It is an object of the present invention toprovide a solenoid which has a suitable housing construction from thepoint of view of strength and which has a novel magnetic circuit for themagnetic flux of the solenoid.

Another object of the invention is the construction of a solenoid inwhich. the physical dimensions, weight and operating temperature are ata minimum for a definite amount of pounds pull or torque. A

In solenoid construction it is extremely desirable to use a magneticcircuit made upof thin v laminae in order to reduce the eddy currentsand keep the iron loss at a minimum. On the other hand, it is desirableto keep the magnetic circuit as short as possible and also to provide ahousing along with the circuit which protects the electric coil bothfrom the point of view of conducting the heat away from the coil andkeeping air and Figs. 2 and 3 are sectional views taken on lines 2-2 and3 4, respectively, of Fig. l.

Figs. 4 and 5 are end and side elevations re-A spectively of themagnetic material which goes into the solenoid.

Fig. 6 illustrates the condition of the housing and magnetic materialprior to the machining operation.

Fig. 7 is asectional view of the construction of Fig. 6.

Fig. 8 is an end view of the housing after machining, showing the recesswhich receives the solenoid in assembly.

Fig. 9 `is a partial perspective of the end plate showing the detailedconstruction thereof.

In Fig. 4, four blocks, A, B, C and D are shown arranged in spacedrelation around an imaginary axis E. These blocks are held in'theirrespective positions by angles i0 and braces Il.

dirt out of the operating mechanism. The so' 30 y ing the casingmaterial into such mold while in a molten or plastic state and thenallowing it to set called window frame type of solenoid construction iswell known, that is, the type in which a frame of laminae is usedtosurround the coil. Another type has recently come into use and that isthe solenoid circular iron housing, this latter type has the advantagesof providing a complete covering for the construction but has causedconsiderable loss from heat due toeddy currents and The presentinvention contemplates a solenoid housing which combines 40 theadvantages of the laminated structure with the solenoid housingstructure and which achieves the ideal result of a minimum eddy currentloss,

low iron loss, a short magnetic path, low operat- 4 ing temperature, andlight weight. There are numerous other advantages which.l iiow from theconstruction to be herein described but no attempt made here toenumerate all the" advantages.

Other objects and features of the invention will These blocks A, B, Cand'D arevformed of a magnetic material and may be of solid iron. Theyare preferably formed of L-shaped pieces of laminations of iron as shownin the drawings. The next step in the manufacture of the housings is theforming of a casing around the magnetic blocks. This casing is shown atl5, Fig. 6. This casing may be applied around the blocks in adie-casting operation or a molding process. Fundamentally, the stepconsists of placing the blocks within some kind of a mold and eitherforcing or pouror harden. A core is used to eliminate the necessity forboring out the entire center. The material forming the housing I5 is tobe a non-magnetic material. Ilf metal is used, aluminum has been foundto be suitable. Another suitable subvstance is the class of materialswhich is commonly called plastics, one of which is Bakelite.

Other suitable means may be used to space and arrange the blocks priorto the molding process. Afterl the casting or molding operation, theblock is machined to have an internal bore I6, as shown in Fig. 8. Thebore does not pass coml pletely through the block but terminates in aWall Il which has an aperture i8. The magnetic circuit of the housing iscompleted by two additional blocks of laminated material F and G, shownin Fig. 2, arranged in transverse relation and jointed 4together in'such a Way that the ends thereof will register with the end blocks A,B, C and D. A cap 20 is provided with a recess for receiving the membersF and G and for positioning the same.

A magnetic pole piece 2| is held against the center portion of theblocks by a bolt 22. The cap The cap 2l with the pieces F and Gcompletes s the magnetic circuits at one end of the assembly while theother ends of the circuits are completed by the portions of blocks A, B,C and D which make up wall l1 (Fig. 8). While the arrangement describedis preferred, it will be seen that separate end pieces could be used atboth ends of the circuits.

A solenoid winding 24 is received in the bore I6 of the housing I5. Anon-magnetic sleeve 2l, for example of brass, is inserted within thesolenoid Winding. This sleeve is sealed at one end by a compressiblegasket 2G and atthe other end by a. compressible gasket 21. Thesegaskets are made slightly oompressible to permit the' parts to be drawntightly together in connection with a member 28a. which forms part ofthe complete assembly and may, for example, be a body of a valve. Withinthe sleeve 25 is the slotted solenoid core 28 which reciprocates backand forth when the solenoid is energized and may be connected to orintegral with the movable member of a valve. Suitable lead wires aretaken from the solenoid core through an opening 29 in the calp 20, seeFig. 2. The ends of the members F and G, are positioned in openings 30machined in the cap 2l (see Fig. 9). It will thus be seen that there isformed a solenoid assembly in which the solenoid core 28 and the insideof the sleeve 25 are sealed from the solenoid. This prevents any oil orforeign matter which may be in the sleeve fromleaking in the winding.I-f desired the members F and G mayalso be cast into the cap 20.

A soft washer 35 is placed =between members i and 2| to seal the insideof the solenoid from dirt and dust. This washer is preferably of thesoft material which will permit the bolts 23 t0 tighten the members Fand G tightly against the ends of the members A, B, C and D of housingIl. It also'permits the sealing of the compressible seals 28 and 21.

It will be seen that the above described construction provides manypaths for the magnetic flux and, in addition, it can ow in more than oneplane. The path, however, of the ux is a short path with a. minimum ofair gaps. In fact, the only air gaps that exist are those between themembers A, B, C and D and the transverse G and F. Since this air gap canbe reduced to a minimum by the forcing of the parts together inassembly, it does not involve a serious loss. Since these air gaps arereduced to a minimum by the forcing of the parts together in assembly,

. the magnetizing current is reduced to a minimum Lthereby diminishingthe no-load losses considerably. Therefore, the windings of the coil canbe maintained at a minimum and more of the effective current put' intothe solenoid is transferred into actual pull. In addition, it will beseen that the solenoid is completely protected from outside dirt and airand that the use of a light-material for the housing, such as aluminumor plastic will reduce the overall weight considerably. In addition, thelaminations are rigidly secured against vibration and loosening.

We claim:

1. A solenoid construction comprising a casing of `non-magneticmaterial, fields of laminated magnetic material embedded in said casingin spaced relation around a central bore therein,v a solenoid winding insaid bore, means at the end of said winding in said bore for forming anend pole comprising longitudinal blocks of laminated magnetic materialarranged in y transverse relation and positioned whereby the endsthereof register with the magnetic material in said main housing, amagnetic pole piece on said blocks, and a cap for maintaining saidblocks in position relative to said main housing.

2. A solenoid construction comprising a casing of non-magnetic materialsuch as aluminum. fields of laminated magnetic material embedded in saidcasing in spaced relation around a central bore therein, a solenoidwinding in said bore, meansat the end of said winding in said bore forforming an end pole comprising longitudinal blocks of laminated magneticmaterial arranged in transverse relation and positioned whereby the endsthereof register with the magnetic material in said main housing, amagnetic polel piece on said blocks, and a cap for maintaining saidblocks in position relative to said main housing, and means holding saidcap in place comprising bolts extending from said cap into saidembedding material independently of said field laminations.

3. A solenoid construction comprising a casing of non-magnetic materialsuch as aluminum, elds of magnetic material embedded in said cas' ing inspaced relation around a central bore therein, said material comprisingL-shaped laminations arranged inv groups, a solenoidwinding in saidbore, means at the end of said winding in said bore foxl forming an endpole comprising longitudinal blocks of magnetic material arranged intransverse relation and positioned whereby the ends thereof registerwith the magnetic material in said main housing, a magnetic pole pieceon said blocks, and means formed of non-magnetic material formaintaining said blocks in position relative to said housing.

4. The method of forming a solenoid housing which comprises arrangingcorner to corner L- ends of elongated blocks of magnetic materialparallel to, and in spaced relation around, an imaginary locus,surrounding said pieces in a non-magnetic material in a plastic state,hardening said `material to embed said blocks firmly, and machiningblocks and the embedding material to provide an opening to receive asolenoid winding. f

5. The method of forming a housing for an electrical device dependent onelectrical fields for operation which comprises arranging pieces ofmagnetic material in spaced relation around an imaginarylocus. fasteningsaid pieces together with suitable means to hold them in spacedrelation, surrounding said pieces in a non-magnetic material in a moltenor plastic state, hardening said material to embed sai-d blocks firmly,and

`machining the magnetic material and the embedding material to providean opening to receive an electrical element.

6. A housing for a cylindrical solenoid winding comprising a pluralityof sets of L-shaped iron laminae arranged in opposed pairs around anaxis, a non-magnetic material embedding said laminae, one leg of eachlamina extending parsaid inierlocked laminae Within said Windcentlyspaced sets to maintain the same in position, means embeddingV saidangle means and said sets of leaving the inward feces oi`'thelaminneexposed,l.pluralityotinterloeked`setsotlaminaeurang'edndiellyoitheaxis,each

set having its ends positioned adjacent the' .ends

of the opposed pairs of L-shsped lamine, and? means on said interiockedlaminae and within said winding to' form l pole piece for s solenoidplunger operating within said winding.

RAYMOND B. MILLER. KAMILL BEIDEL.

